Erratic and jerky hydraulics

[pcolyer4]

Hello everyone. I bought a used Jinma 254-2 (all I could afford) and the previous owner said it blew a hydraulic hose and he replaced it and since the hydraulics are erratic and jerky for the FEL and 3-point. I assumed he had burned up the pump so I replaced it and all the hydraulic fluid and it's doing the same exact thing as it was, you must raise the rpm's and the raise and curl functions are jerky like there's air in it. Does anyone know what may be causing this? It supposedly worked smoothly as it should before the hose blew! Thank you in advance.
Paul

 

[repete]

Which hose did the previous owner replace?

 

[pcolyer4]

I think it was to raise bucket but not 100%

 

[Mike1955]

Pro I assume this issues is resolved. I was going to point out the only time I ever had that problem was that it was due to air in the lines. Fix it by keep operating it

 

[Fred in BC]

As Mike said, it sounds like air in the lines.
If there's air in the system when you fill the reservoir, it may take a while to work out of the system.
Go to full lift on the loader, then all the way back down. Check and fill the hydraulic oil.
Run the 3 point full up and full down several times. Same with anything else hydraulic. If things run a little smoother, you know you're on the right track.

 

[RayIN]

As Mike said, it sounds like air in the lines.
If there's air in the system when you fill the reservoir, it may take a while to work out of the system.
Go to full lift on the loader, then all the way back down. Check and fill the hydraulic oil.
Run the 3 point full up and full down several times. Same with anything else hydraulic. If things run a little smoother, you know you're on the right track.

Yep, operate all cylinders, both ways to full-stop, while never allowing hyd, oil level to fall to the add mark.

 

[pcolyer4]

I'm sorry for not responding, I never received any replies until all at once days later. I have been running all the functions of fel, 3-point and steering and the problem hasn't gotten any better. Someone had said about the quick connections and they may be causing this and another suggests putting a gauge immediately after the pump to assure it's working properly even though it is new but it's doing the same thing as when I got it and I just assumed he may have inadvertently burned it up after blowing the hose but he assured me it was operating normally before the line blew...

 

[oldnslo]

Triple check all of connections on the inlet line to the pump to confirm they are tight and not leaking any air when under vacuum. If there is a rubber hose on the pump inlet check that for cracks or if soft and collapsing under vacuum.

 

[pcolyer4]

Hello and thank you for your reply. When you say inlet do you mean the suction side of the pump going from the filter/reservoir to the pump with a rubber hose and 2 hose clamps? Or the pressure side going to the distribution manifold which I believe holds the pressure relief valve?

 

[pcolyer4]

This pic is from the pressure side and has a smaller hose?